Magnetic systems of the type described above are used, for example, in electromagnetic drives, such as permanent and hybrid drives, in magnetic distance and angle measurement systems, in magnetic couplings and valves and in magneto-sensitive sensors. In the course of miniaturization, these systems must be made smaller and smaller while achieving similar performance, or they must retain the same size while achieving ever-increasing performance. On one hand, magnetic systems are required that can be adapted visually to the measurement systems or the functional geometry of these systems. These systems can be both flat, two-dimensional magnetic films as well as magnet systems with a complex three-dimensional external shape. On the other hand, high-output magnetic materials such as rare-earth magnetic materials, in particular NdFeB, are being used. The advantage of NdFeB magnetic systems is that even at low magnetic film thicknesses, a high magnetic actuation and high B-field can be achieved in the magnetic circuit. NdFeB has a high magnetic hardness and a low demagnetization. Furthermore, a uniform overall magnetization of the magnet segments is desirable, to achieve the sharpest possible transition between two neighboring, oppositely polarized magnetic segments.
A disadvantage with the use of NdFeB magnetic systems is that magnetic field strengths of up to more than 500 kA/m and correspondingly high magnetization currents must be used for the production of the magnetic segments. In conventional magnetization devices, the magnetization of these magnetic systems is realized in a process by means of pulse magnetization with a short heavy current pulse by a magnetizer coil that is specially adapted to the magnetic system A disadvantage of this method is that on account of the extremely high magnetization currents, correspondingly large line cross sections are necessary for the coils, and that is a limiting factor for the distance between pole centers and thus for the integration density of the magnets. By means of this method, it becomes possible to manufacture magnetic systems with strip-shaped, multipole magnetization and distances between pole centers of 2 or 1 mm.
For example, as described in the publication “Micromachining and Microfabrication” in Proc. SPIE Vol. 3680B-65, for the manufacture of the disc rotor motor and its rotor disc described in the two German patent applications DE 199 02 370 and DE 199 02 371, a magnetic ring was manufactured by molding from NdFeB magnetic material. This ring was then multipole magnetized completely in a conventional pulse magnetization device with a coil shaped to correspond to the magnetic segments to be formed. On one hand, magnetic field losses are found in the peripheral areas between two magnetic segments, and on the other hand, the configuration of the magnetic surface is already significantly restricted by the fact that almost no magnetization takes place in areas of the coil windings.
With conventional shapes of the magnetization coils, moreover, complicated shapes of magnetic systems cannot be magnetized in a single process. As an alternative, the magnetic segments are produced individually, whereby magnetization heads generate part of the required magnetic field strength. A disadvantage of this method is that it is a serial process, and therefore requires a good deal of time to complete. Furthermore, to achieve the necessary saturation, a minimum distance must be maintained between the magnetic head and the surface to be magnetized, which is a limiting factor in the reduction of the distance between pole centers. Moreover, the very high forces that occur during the magnetization process place mechanical loads on the magnetization heads, which means that the magnetization heads must be provided with complex retaining and support structures.
To eliminate the problems of the magnetization of miniaturized magnetic systems described above, DE 195 33 120 A1 and the corresponding publication in the journal “Feinwerktechnik und Mikrotechnik, Mikroelektronik (FuM)” 105 (1998) 4, p. 194 ff., Carl Hanser Verlag, for the formation of a magnetic position sensor, describe a magnetic disc or a code carrier and a method for its manufacture, whereby the code carrier consists of two parts with a tooth structure on the periphery. The two parts are radially magnetized separately from each other, one part with the magnetic north pole on the outside periphery and the other part with the south pole on the outside periphery. When the two parts are put together, the desired alternating magnetic field is formed. One disadvantage with this process is that to assemble the code carrier, molded joint structures are required, which in this case are in the form of tooth structures. These joint structures also limit the further miniaturization of the code carriers.